Cyclosporine A (Sandimmune) (CSA) is a cyclic undecapeptide containing the novel amino acid, 2S-N-methyl-3R-hydroxy-4R-methyl-6E-octenoic acid, abbreviated MeBmt. Cyclosporine A constitutes a basic innovation in immunology and related fields, with potential applications for treatment of long term chronic autoimmunity diseases if less-toxic analogs can be found. The objective of this competitive renewal is to continue the chemical synthesis of novel CSA analogs and to develop the chemistry necessary for their synthesis. The work will begin by extending our discovery of the BOP-C1 coupling method for coupling N-methyl amino acids together in solution to the stepwise synthesis of CSA both in solution and on solid phase resins. Our new methods for synthesizing optically active 2N-methyl-3-hydroxy amino acids will be extended to the synthesis of 2S-N-methyl-3R-hydroxy-4R-methyl-6E-octenoic acid, and to analogs of this amino acid. These novel amino acids will be incorporated into the 1-position of CSA. Our successful synthesis of CSA will be modified to permit the design and synthesis of conformationally constrained analogs of CSA that will permit us to determine conformational features of the bioactive conformation of CSA needed for selective binding at its receptors. Three types of analogs will be synthesized: bicyclic disulfides; dipeptidyl lactams and bicyclic N-alkylsubstituents. The appropriate control peptides containing standard amino acids will be synthesized as standards. The synthetic analogs will be assayed for inhibition of ConA stimulated thymocytes, for inhibition of antigen drive proliferation, and for binding to calmodulin and cyclophilin. A major emphasis will be to try to determine if selectivity for individual receptors is possible as this will point the way to the synthesis of less toxic analogs useful in the treatment of chronic autoimmune diseases. The design of the analogs will be carried out using the SYBYL molecular graphics software on our Evans Sutherland PS-300. NMR data will be obtained at 500 MHz to establish product structure and conformational similarity to CSA.